Internal Structure of Concrete Prefabricated Houses

The internal structure of concrete prefabricated houses is centered around modularization and standardization, achieving efficient construction and functional guarantees through structural systems, connection techniques, moisture-proof designs, and material optimization. The specific structural highlights are as follows:

1. Structural System: Integrated Load-Bearing Framework

Concrete prefabricated houses adopt a full-frame shear wall structure, with the main body formed by C35 concrete and Φ8-Φ14 threaded steel bars poured in one go using molds, creating an integrated load-bearing system of L-shaped columns + rectangular beams + floor slabs. This structure achieves high-precision processing through factory prefabrication, ensuring component dimensional errors are controlled within millimeters. After on-site hoisting, a stable framework is directly formed without the need for secondary formwork pouring. Among them, the L-shaped columns enhance lateral force resistance through optimized cross-sectional design, while the rectangular beams and floor slabs work together to withstand vertical loads (such as personnel and equipment weight) and horizontal loads (such as wind and earthquake forces), with the overall structural strength reaching over 90% of that of traditional cast-in-place concrete.

2. Modular Design: Functional Integration and Rapid Assembly

Each prefabricated module completes core functional integration in the factory:

• Embedded Plumbing and Electrical Lines: Circuit pipes (PVC pipes) and water supply and drainage pipes (PPR pipes) are pre-laid within the modules, with interface positions reserved to avoid on-site trenching that could damage the structure;
• Integrated Insulation Layer: 50-100mm thick EPS boards are used as wall insulation layers, combined with the concrete layer through adhesives to optimize thermal performance;
• Waterproof Testing: Modules undergo a 24-hour closed-water test before leaving the factory to ensure no leakage at joints;
• Rapid Assembly: After module hoisting, it takes only 3 days to complete the connection of water and electricity, reducing the traditional construction period by over 60%.

3. Connection Techniques: High-Strength Nodes Ensure Integrity

Modules are rigidly connected through prestressed bolts + welded steel plates:

• Prestressed Bolts: High-strength bolts (such as Grade 8.8) are used to apply pre-tensioning force, with a single-point tensile strength of 20 tons, ensuring nodes do not loosen under load;
• Welded Steel Plates: Thickened steel plates (thickness ≥ 10mm) are set at module joints, forming a continuous load-transfer path through full-welding processes to enhance overall bending and shear resistance;
• Seismic and Wind Resistance: Connection methods are adjusted according to floor height, with low-rise houses achieving a wind resistance rating of Level 12 and seismic fortification intensity of Levels 7-9 (e.g., reinforced connection nodes are used in areas with a seismic fortification intensity of Level 8).

4. Moisture-Proof Construction: Multi-Level Protection System

In response to the hygroscopic nature of concrete materials, a four-level moisture-proof design is implemented:

• Foundation Moisture Proofing: A gravel or crushed stone bedding layer (thickness ≥ 200mm) is laid at the foundation bottom to form drainage channels, with an asphalt coating or polyethylene film (thickness ≥ 0.5mm) set above the foundation to block capillary rise of groundwater;
• Wall Moisture Proofing: Module joints are filled with silicone sealant, with the exterior surface coated with polyurethane waterproof coating (coating thickness ≥ 1.5mm), and a skirting board or moisture-proof strip (height ≥ 150mm) set at the junction of walls and floors;
• Floor Moisture Proofing: A moisture-proof film (such as polyethylene film) is laid on the base layer, followed by pouring a C20 concrete surface layer (thickness ≥ 80mm); in humid areas, an elevated floor (height ≥ 300mm) can be set to isolate soil moisture;
• Ventilation Design: Indoor air circulation is maintained through windows, vents, or exhaust fans, with relative humidity controlled below 60% to prevent condensation accumulation.

5. Material Characteristics: Density and Durability Optimization

The main materials are cement, sand, gravel, and steel bars, with performance enhanced through the following processes:

• Water-Cement Ratio Control: The water-cement ratio is strictly limited (≤ 0.5) to reduce internal pores in the concrete;
• Admixture Addition: Water reducers and air-entraining agents are added to improve concrete workability, while introducing tiny bubbles (diameter < 1mm) to enhance frost resistance;
• Density Enhancement: High-frequency vibration tables are used for vibration to ensure the concrete density reaches 2400kg/m³ or more, with compressive strength increased by 15%-20% compared to ordinary concrete.